Review/Oorsig Volume 22, Issue 05 - Page 15

Volume 22 • Issue 05 • 2018 cheeses and butter contain very little Lactose. These dairy products can as a result be consumed by Lactose-intolerant individuals without causing discomfort. WHY LACTOSE? In the case of sour milk, Lactose is broken down by bacteria (that have the enzyme β-galactosidase) into Glucose and Galactose that is fermented into lactic acid. Even though yoghurt still contains Lactose, the levels of Lactose is reduced sufficiently through fermentation to not cause symptoms in most people with Lactose- intolerance. Newborn mammals have sufficient sup- plies of lactase to digest the Lactose in milk. As the baby matures the produc- tion of lactase starts to decline. This leads to undigested Lactose ending up in the large colon, which in turn leads to bloat, flatulence, discomfort and diar- rhoea. Partly due to the osmotic effect of Lactose and partly due to bacteria in the colon fermenting Lactose and producing gas in the process. Because Lactose is a major osmole in milk, accounting for approximately 50% of milk’s osmolality, its levels tend to remain stable in milk. Any change in the Lactose levels need to be considered as significant and need to be investigated The question arises as to why did na- ture settle on Lactose instead of one of the simpler sugars such as Glucose or Sucrose? One theory postulates that it is because it takes a lot of energy for a mother to breastfeed as well as sus- tain her own energy levels. Should she become pregnant while still breastfeed- ing, her reserves will be diverted to the developing foetus at the expense of producing breastmilk. This will decrease the chances of survival of the child being breastfed. Although goats milk only has approximately 10% less Lactose than cow’s milk, countless people with Lactose-intolerance can consume goat’s milk without adverse effects. The reason is not quite clear WHAT AFFECTS LACTOSE LEVELS IN COW’S MILK? Lactose is the primary osmole in milk. Anything that affects Lactose production will affect milk yield. • • • • • Lactose is quite insensitive to changes in diet composition. Underfeeding being the only part of diet that affects Lactose levels. Lactose is made from Glucose which acts as an energy source of the cow. If total energy and dry matter intake is restricted (or low quality forage is used) it will lead to a reduction in Lactose production. Lactose levels drop towards late lactation There is a slight day to day variation in Lactose levels of approximately 0.07 - 0.09 percentage units Stress can reduce Lactose levels There is a high correlation between a high SCC (Somatic cell count) and reduced Lactose levels. Low Lactose levels is a very accurate predictor of subclinical mastitis. Anything that addresses the above points will improve milk production by increasing the lactose production. While a mother is breastfeeding there is a negative hormonal feedback which suppresses ovulation and hence her chances of falling pregnant. This gives the suckling offspring sufficient time to develop to the stage where it can consume solid foods. At that stage the lactase activity starts to decline, causing discomfort for the offspring whenever it breastfeeds. This discomfort aids in weaning the child. After weaning the negative hormonal feedback disappears and the mother starts to ovulate again. The conclusion is that Lactose is nature’s way of regulating the time between pregnancies to optimise the frequency of reproduction, without endangering the chances of survival of any of the offspring. 15